1. Field of the Invention
The present invention relates to an image forming apparatus, an image formation controlling method, and a computer readable medium storing instructions for performing the image formation controlling method.
2. Discussion of the Background
Image forming apparatus such as printers, copiers, complex image forming machines include a controller and an engine. For example, in electrophotographic image forming apparatus, the engine includes a print processing section, which performs print processing on a receiving material such as paper sheets according to image data using print process devices including a photoreceptor, a charger, an optical writing device, a developing device, a separating device, a fixing device, a cleaner, etc.; and a controlling device. The controlling device of the engine is configured to communicate with the controller to receive control signals, image data and a print request, which are necessary for image formation processing (i.e., print processing). Next, the controlling device performs image formation controlling so that the charger uniformly charges the entire surface of the photoreceptor; the optical writing device imagewise irradiates the charged photoreceptor with light to form an electrostatic latent image thereon; the developing device develops the electrostatic latent image with a developer including a toner to form a toner image on the photoreceptor; a receiving material feeding device feeds a sheet of a receiving material; the transfer device transfers the toner image on the photoreceptor onto the thus fed receiving material sheet; and a fixing device fixes the toner image on the receiving material sheet upon application of heat and pressure thereto, resulting in formation of the image on the receiving material sheet. Such an image forming apparatus is disclosed, for example, in a published unexamined Japanese patent application No. 2002-49202.
In one printing job of such a background image forming apparatus, the time (i.e., next print request waiting time (or waiting time)) from receipt of a print request from the controller and start of the print processing to the next print request is checked to determine whether or not the next print request is made within the waiting time. If the next print request is not received from the controller within the waiting time, the controlling device of the engine judges that the image data under processing are the last page data of the print job, and performs a termination processing in which the above-mentioned series of printing processes (print process devices) are terminated. When a next print request is received from the controller in this termination processing, the image forming apparatus cannot start the start-up (initiation) processing for the next print process. Therefore, in this case, after the apparatus completes the termination processing for the former print process, the apparatus starts the start-up processing for the next print process.
Specifically, if the data sent to the controller are such that the time needed for forming image data from the data in the controller is relatively long, a problem in that the next print request for the image data is not sent to the engine within the waiting time occurs. In this case, the apparatus starts to perform the termination processing. Therefore, the print processing for the next image has to be performed after the termination processing and the subsequent start-up processing for the next print process, resulting in reduction of the print speed and productivity of the image forming apparatus. In addition, another problem in that due to repetition of the termination processing and the subsequent start-up processing, the lives of the image forming parts of the apparatus shorten occurs.
Because of these reasons, a need exists for an image forming apparatus in which the number of times of the termination processing and the subsequent start-up processing is decreased to increase the print speed and to prolong the lives of the image forming parts of the apparatus.